A machine may include a transmission coupled to a power source, such as an internal combustion engine or an electric motor, to enable the machine to be repositioned and/or to travel between locations. With increased interest in energy conservation and avoidance of use of fossil fuels, use of electric motors is becoming more common. Electric motors may be used to convert electrical energy into mechanical power to drive the machine. For example, electric motors may be used in a vehicle, a backhoe loader, a cold planer, a wheel loader, a compactor, a feller buncher, a forest machine, a forwarder, a harvester, an excavator, an industrial loader, a knuckleboom loader, a material handler, a motor grader, a pipelayer, a road reclaimer, a skid steer loader, a skidder, a telehandler, a tractor, a dozer, a tractor scraper, or other equipment.
Alternatively, some machines may include both an electric motor and an internal combustion engine. For example, an electrical drive train of a machine, such as a tractor, may include an internal combustion engine, a generator coupled to the internal combustion engine, a direct current (DC) power source, and a motor. In this case, the internal combustion engine may be used to reposition the machine, and the generator, the DC power source, and the motor may be used to drive one or more implements of the machine.
The motor may be a switched reluctance (SR) motor. An amount of current provided to the switched reluctance motor may be controlled based on an operating mode of the switched reluctance motor. For example, a controller may implement a current regulation operating mode, such as for lower speed (e.g., less than a threshold speed) tasks that require greater amounts of motor torque (e.g., greater than a threshold motor torque value). In the current regulation operating mode, the controller may limit current in connection with an amount of back electromotive force from the switched reluctance motor, thereby resulting in a constant motor torque being achieved at increasing motor speeds.
In contrast, the controller may implement a single pulse operating mode for higher speed tasks requiring greater amounts of power output relative to the current regulation mode. In the single pulse operating mode, the controller may sequentially advance a phase of current provided to the switched reluctance motor to maintain a constant power at increasing motor speeds and decreasing levels of motor torque.
Further, the controller may implement a continuous conduction operating mode, which may be defined by a fixed dwell. The fixed dwell, sometimes termed a static dwell, may represent a conduction window during which voltage is applied to each phase of the switched reluctance motor, and may correspond to a difference between a theta on angle at which voltage is applied and a theta off angle at which voltage is not applied. The theta on angle and theta off angle may represent positions of the switched reluctance rotor, of the motor, relative to a stator, of the switched reluctance motor. The dwell may be fixed at an angle greater than 180 degrees (e.g., 181 degrees, 182 degrees, 185 degrees, etc.), thereby providing a transient over-torque for a fixed DC voltage. In this way, the controller may enable increased motor power to achieve increased motor speed relative to the single pulse mode at decreased levels of motor torque. However, a transition between a single pulse operation mode and a continuous conduction operation mode with a fixed dwell may result in a hard transition in a motor torque at some load conditions.
One attempt to improve motor controllers is disclosed in United States Patent Application Publication No. 2014/0184131 that was filed by Samsung Electro-Mechanics Co., LTD. on Dec. 26, 2013 (“the '131 patent publication”). In particular, the '131 patent publication discloses a method of controlling a switched reluctance motor. The method, disclosed in the '131 patent publication, includes sensing a variation of a load of a switched reluctance motor and controlling both a dwell angle and a pulse width modulation duty ratio of the switched reluctance motor.
However, controlling both a dwell angle and a pulse width modulation duty ratio of a switched reluctance motor may not enable optimized control of a switched reluctance motor at differing motor speeds, motor torques, powers, and/or the like. A switched reluctance motor control system for operation mode selection of the present disclosure solves one or more problems set forth above and/or other problems in the art.